When it comes to plane etiquette, the unspoken rules and courtesies can be quite confusing. With narrowing seats and shrinking legroom in airplanes, the issue of personal space has become more contentious among passengers.

One of the common sources of air rage cases between cabin mates is the armrest. In 2017, a man and a woman reportedly got into a screaming match in a Monarch Airlines flight from London to Malaga over an armrest between the aisle and middle seats. Last year, a woman posted a video on Twitter of her seatmate on an American Airlines flight who was allegedly “making an active scene” over their arms touching. The video went viral with more than 453,000 views.

 So, who should have the right to the armrest? While there are no hard and fast rules, there are some customs that many deem fairer than others.

Most experts believe the middle seat should have both armrests. “The person seated at the window seat has their own armrest and wall, along with the person seated in the aisle seat – they also have a little more leg room,” Zarife Hardy, director of the Australian School of Etiquette told 9Honey Travel.

“So, the person or people seated in the middle generally get the armrests first … However, let's keep it fair and just wait to see how it casually and politely happens.”

Flight attendant Jacqueline Marie shared the sentiment. “I one hundred percent believe the middle seat has the right to both armrests,” she told The Points Guy.

“I view the armrests as boundary lines but, shockingly, as a flight attendant I have never been asked to fix a dispute regarding seat space. But you know the sad thing? I honestly feel like many of those who get stuck in the middle just hope for a peaceful flight and they avoid confrontation, even if it means they will not be as comfortable.”

According to Christopher Elliott, journalist and co-founder of advocacy group Travelers United, the armrests are still a shared space – but the middle seat should have priority.

“If you're sitting in a window or aisle seat, the middle seat passenger gets to put his arms down first,” he wrote on the Washington Post. “If there's room left over, great. If not, it belongs to the middle seat passenger.”

But what about situations when we feel like a seatmate has invaded our space?

Gary Leff, co-founder of suggested to observe the situation. If there is another empty seat in the cabin, you can ask a flight attendant discreetly if you can move – however, this scenario is unlikely to happen on a crowded flight. 

“If your seatmate could easily take up less space, try to start a polite conversation and mention that you’d appreciate some of the armrest,” said Leff.

However, if they unwillingly take up more space due to their body size, Leff suggested there is not much that you can do. 

“The only time to enlist the help of the flight attendant is as a last resort. A flight attendant isn't going to stay by your seat through the flight to monitor your seatmate's behaviour. But if the person is clearly abusive, getting it on record with the crew can be a prophylactic measure.”

Have you ever dealt with armrest problems on the plane?

Ill images: Getty Images. This article originally appeared on Over60.